The brake pedal which is used to decelerate or stop the speed of a vehicle during the driving of the vehicle, in general, is formed of a brake pedal configured to be pedaled by a vehicle driver, a booster which is a boosting component configured to receive and multiple an operational pedal effort of the brake pedal, a master cylinder configured to create a hydraulic pressure in such a way to pressurize oil through the booster, and a wheel brake equipped with a wheel cylinder configured to regulate a disk drum of a wheel with the aid of the master cylinder.
The brake pedal is configured to operate based on the principle of a lever. The brake pedal is installed about an action point. If a driver works a pedal, the force applied from a fixing point to a push rod may allow to push the piston of a master cylinder through a booster, thus creating a hydraulic pressure, and this hydraulic pressure may be constantly transferred to the cylinder of each wheel brake, by which a braking force can be operated.
The booster is referred to a device which is able to multiple the pressure of a driver transferred from a brake pedal to a master cylinder, namely, a boosting component which is able to increase a brake operational force. A vehicle which weighs heavy like a large size truck, in general, is equipped with a vacuum compressor, wherein an indirect operation of a hydro vac type in terms of the operation of a booster is employed. In case of a common passenger vehicle, a direct operation of a maser vac type is employed, wherein the booster is driven using the vacuum created from an intake manifold of an engine.
The master cylinder is referred to a component which is able to convert a pedal effort corresponding to the pedaling force of a brake pedal into a hydraulic pressure, wherein a brake liquid and a piston are disposed inside of the master cylinder, and the created hydraulic pressure is transferred to a wheel cylinder through a brake pipe, and the piston inside of the wheel cylinder is pushed backward by the hydraulic pressure, thus pushing a brake shoe or a brake pad toward a drum or a disk, by which a braking force can be created. This master cylinder may be categorized into a tandem type wherein two master cylinders are disposed in series to resolve a problem wherein a brake doesn't work if a defect occurs, for example, the leakage of a brake liquid in a hydraulic pressure system and to enhance a safety; a stepped tandem type wherein the pistons of different diameters are employed, and if one circuit is broken, the pressure of a normal circular increases, thus supplementing the lack of a braking force; a central valve type (a tandem master cylinder with a central valve) wherein this is employed at a vehicle equipped with an ABS (Anti-lock Brake System), and a central valve installed at the piston carries out the function of a compensation port; and a residual pressure check valve (a residual check valve) wherein this can be employed in case where a cup seal is used at a wheel cylinder of a drum brake, and this can be assembled to a brake pipe or a master cylinder and a brake pipe or can be installed inside of the master cylinder.
For the sake of a deceleration and stop during the driving of a vehicle, the vehicle is equipped with a wheel brake which is able to brake front wheels and rear wheels, a booster which is a boosting component to transfer an operational pressure to the wheel brake by forming a braking hydraulic pressure, and a master cylinder. If a vehicle driver works a brake pedal, a braking force may be created as a small force is transferred to a wheel brake which includes a booster configured to boost (multiple) a small force which has been applied to a brake pedal, a master cylinder which is a hydraulic pressure component configured to convert a large force into a hydraulic pressure and constantly transfer a pressure (a hydraulic pressure) irrespective of the distance to a braking device, a hydraulic cylinder having a large area for the transferred hydraulic pressure to have a large force, and a brake pad having a good friction force.
Meanwhile, since the braking performance of the vehicle is directly associated with safety, a manufacturer is carrying out an inspection with respect to the components which form a braking system.
As an example of a conventional braking performance inspection technology, the Korean patent registration number 10-0405569 discloses “a braking performance evaluation and test device”. According to Claim 1 thereof, the braking performance evaluation and test device is formed of a wheel speed sensor configured to detect if a vehicle is being driven; a brake pedal sensor configured to detect if a brake pedal is being operated; a pressure sensor configured to detect a braking pressure supplied via a brake pipe when a braking force is created by a vehicle which is being driven, an electronic controller wherein a target braking pressure set based on a condition and kind of a braking performance evaluation and test is inputted, and a target time which is necessary to reach the target braking pressure is inputted, and a braking pressure maintaining time to constantly maintain the target braking pressure until the braking is completed, is inputted; an assistant braking hydraulic generation unit which is installed connected to the brake pipe and is configured to be selectively driven in response to a control of the electronic controller and to create an assistant braking hydraulic pressure; a first pressure control value configured to control an open route with the aid of a control of the electronic controller in order for a braking hydraulic pressure created by the operation of the brake pedal and an assistant braking hydraulic pressure created by the driving of the assistant braking hydraulic pressure generation unit to be selectively supplied toward a brake main body based on the braking performance evaluation and test step; and a plurality of second pressure control valves which are installed at the brake pipe connected to the brake main body of the front wheel and at the brake pipe connected to the brake main body of the rear wheel and are configured to be selectively opened or closed in response to a control of the electronic controller based on the braking performance evaluation and test step.
The aforementioned conventional technology braking performance evaluation and test device has a problem in the way that a vehicle having a good braking performance can be developed in such a way to obtain a braking performance data calculation and collection at the vehicle development stage; however it is impossible to check any abnormality in various components which form the braking system. More specifically, the conventional braking performance evaluation and test device cannot be used for the purpose of confirming a braking performance state of a vehicle after it has been installed at a common commercial vehicle.
Moreover, as another conventional technology, the Korean patent registration number 10-0348040 discloses “a performance test device for a brake booster”. According to Claim 1, the performance test device for a brake booster is formed of a shelf member; an engaging unit formed of an arm member engaging bracket hinged with an arm member fixed rotatable at the other side to move after it has been hinged to a driving rod of a braking booster at one side, wherein the engaging unit allows to install the arm member and the booster on the shelf member at a predetermined distance between them; a vacuum unit configured to convert the inside of the booster into a negative pressure state; and a confirmation unit configured to check a braking state of a wheel based on the operation of the booster.
The thusly configured performance test device of a brake booster is configured to check out the performance of the brake booster before it is installed at a vehicle, thus preventing the use of a defective product; however it is impossible to judge if the brake booster has any performance problem after it has been installed at a vehicle which is currently in operation.
Since most of the conventional braking performance test devices of a vehicle are used for the purpose of evaluating the performance of each component forming a braking system at the stage of a vehicle manufacturing or for the purpose of judging any defective problem before a corresponding component is installed at a vehicle, so it is impossible to check out any abnormality in terms of a braking performance with respect to the newly released vehicles. For this reason, it urgently needs to develop a new device which is able to resolve the aforementioned problems. More specifically, the performance of a vehicle may be degraded or the vehicle may be damaged as each component forming the vehicle is aged due to the driving of the vehicle. The information on, for example, an engine revolution, an engine temperature, the amount of fuel, a battery state, the temperature of a cooling water, a speed meter, etc. which are related with the driving performance of the vehicle are provided in real time to a vehicle driver; however the information related with the braking performance for the sake of stop and deceleration is not provided. For this reason, if any problem occurs in the braking system during the driving of the vehicle, a serious problem may occur. Moreover, in case of a safety inspection which is regularly carried out with respect to all the vehicles, only the defects on the lighting state of a braking light and the amount of a brake oil are checked out. The inspection with respect to the braking performance is not carried out.
In the conventional technology, since the vehicles are driven without specifically checking out any abnormality in the braking system, a driver's safety may not be not secured, thus causing a serious problem.
The braking force of a vehicle when it is first released, is good; however, as time passes, the braking force may be gradually degraded. Since the driving force of the engine is regularly checked out from the release of a vehicle to the end of its service life, the performance of the engine can be maintained constant. More specifically, the driving performance of the vehicle can be maintained through a regular vehicle inspection and management; however, the braking performance of the vehicle is not appropriately managed since there is not any inspection criteria, for which an appropriate measurement thereon is urgently necessary.